1. Technical Field of the Invention
The invention generally relates to the field of selectively removing and recovering lithium from lithium containing solutions. More particularly, the invention relates to a composition, methods of preparing the composition, and methods of using the composition for the selective removal and recovery of lithium ions from a lithium ion containing solution, such as a brine, preferably without the removal of other ions from the solution.
2. Description of the Prior Art
Approximately 75 to 80% of lithium chloride, lithium carbonate, and derivatives thereof are produced from lithium that is recovered from brines, frequently via natural evaporative processes. The invention described herein is applicable to these and other such brine sources.
Geothermal brines are currently of particular interest for a variety of reasons. First, many geothermal brines can be used to provide a source of electrical power due to the fact that hot geothermal reservoirs are stored at high pressure underground, which when released to atmospheric pressure, can provide a flash-steam. The flash-stream can be used, for example, to run a power plant. In some geothermal waters and brines, associated binary processes can be used to heat a second fluid, which can provide steam for the generation of electricity without the flashing of the geothermal brine. Finally, many geothermal brines contain various useful and valuable elements dissolved therein, which can be recovered and utilized for secondary processes.
It is known that geothermal brines frequently include various metal ions dissolved therein, particularly alkali and alkaline earth metals, as well as certain transition metals such as manganese, lead, silver and zinc, in varying concentrations, depending upon the source of the brine. Recovery of these metals is potentially important to the chemical and pharmaceutical industries. Typically, the economic recovery of metals from natural brines, which may vary widely in composition, depends not only on the specific concentration of the desired metal within the brine, but also upon the concentrations of the various interfering ions, particularly silica, calcium and magnesium, because the presence of interfering ions can drastically increase recovery costs as additional steps must be taken to remove the interfering ions.
As lithium has gained importance as an element for use in various applications, such as for use in batteries and pharmaceutical compounds, research has focused on developing simple and inexpensive methods for the recovery thereof. For example, Burba previously developed two- and three-layer lithium aluminates for the recovery of lithium from brines. (See, for example, U.S. Pat. Nos. 4,348,295 and 4,461,714; each of which is incorporated herein by reference in their entirety). Certain prior art methods that employ packed columns for the recovery, however, suffer from many drawbacks, such as inefficient lithium extraction capacities and shortened lifetimes due to the slow deterioration and/or disintegration of the particles.
It is known that different forms aluminum hydroxide (which may be present in crystalline, polycrystalline, polymorphic, or amorphous forms) and their intercalated compounds such as [LiX]0-1[Al(OH)3]2, (wherein X is an anion) (hereinafter “lithium aluminum intercalates”, or “LAI”) can be used to selectively recover lithium values from brines. In traditional two-dimensional layered structure aluminum hydroxides, the layered structure facilitates intercalation of anions between the layers, while the positively charged lithium cation can diffuse into the hexagonal cavities formed within the two dimensional layer structure that readily accommodate ions the size of lithium.
While compositions prepared from two-dimensional forms of aluminum hydroxide can be used to extract lithium values from brines and other lithium containing solutions, there currently exists the need for the development of improved methods and compositions for the selective recovery of lithium from lithium containing brines, particularly compositions that are easy to synthesize, have a high capacity for the extraction of lithium, and have good long term physical stability.